JPS6361294B2 - - Google Patents

Abstract

A continuous process is disclosed for preparing 2,2,2-trifluoroethanol from 2-halo-1,1,1-trifluoroethane, preferably 2-chloro-1,1,1-trifluoroethane. In the process, 2-halo-1,1,1-trifluoroethane, a carboxylic acid salt and a hydroxylated compound such as water are continuously provided to a reaction mixture in a reactor. The 2-halo-1,1,1-trifluoroethane, the carboxylic acid salt and the hydroxylated compound are reacted therein at a reaction pressure at or above the autogenously developed pressure and at a reaction temperature of from about 223°C to about the critical temperature of the hydroxylated compound. At least a portion of the reaction product mixture is continuously withdrawn from the reactor and unreacted 2-halo-1,1,1-trifluoroethane is separated therefrom. The separated unreacted 2-halo-1,1,1-trifluoroethanne is recycled as part of the 2-halo-1,1,1-trifluoroethane provided to the reaction mixture. The 2,2,2-trifluoroethanol is recovered from the reaction product mixture.

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing 2,2,2-trifluoroethanol. In particular, the invention relates to a process for the continuous production of such products. 2,2,2-trifluoroethanol is the starting material for the synthesis of various products, including the inhalation anesthetic isofuran (CF ₃ CHClOCHF ₂ ). 2, 2,
Various methods have been disclosed for producing 2-trifluoroethanol. For example, Laura
(Lawlor et al., US Pat. No. 2,868,846) discloses that pH 3
2,2,2-trifluoroethanol can be produced by heating 2-chloro-1,1,1-trifluoroethane in a reaction medium containing a hydroxylated solvent maintained at ~10 A method is disclosed. Lawlor et al. state that in order to effect the reaction, the reaction mixture is heated, preferably at a temperature of 175 DEG to 300 DEG C., and preferably under autogenous pressure. All reactions specifically disclosed in the Lawlor et al. patent are carried out in batches in stirred autoclaves. Also, in the examples of Lawlor et al., the product and unreacted 2-chloro-1,1,
The 1-trifluoroethane can be distilled directly from the autoclave after substantial depressurization or the liquid product can be fractionated to produce the 2-trifluoroethane.
Chloro-1,1,1-trifluoroethane and 2,
2,2-trifluoroethanol is collected separately. A similar method performed in batches is published in Chemical Abstracts Vol.69.
Abst.No.51575y (1968); Chemical abstracts Vol.99, Abst.No.212148y
(1983); Chemical Abstracts
Abstracts), Vol. 100, Abst. No. 34138z (1984). Astrologes US Patent No.
No. 4434297 discloses a two-step process for producing 2,2,2-trifluoroethanol. The astrologes method uses a substantially anhydrous solvent, e.g.
-2-chloro- in methyl-2-pyrrolidone
1,1,1-trifluoroethane is reacted with an alkali metal salt of a carboxylic acid to produce a carboxylic acid ester of 2,2,2-trifluoroethanol and an alkali metal chloride. This ester is then reacted with an alkali metal hydroxide or basic salt in water to produce 2,2,2-trifluoroethanol and an alkali metal salt. The alkali metal salt is then said to be recycled for further reaction. The Astrologes patent suggests that the patent's manufacturing process can be carried out continuously, but no details are given regarding the same. The patent states that the Astrologes method
It specifies that it must ^be carried out at a temperature below 200°C and that it is desirable to maintain a pressure below about 500 psig as the astrologes reaction proceeds. Moreover, all of the Astrologes examples require long reaction times, typically 3
indicates that ~10 hours and more are required. Other earlier methods of producing 2,2,2-trifluoroethanol include, for example, trifluoroacetic acid or trifluoroacetyl chloride or 2,2,2-trifluoroethyl trifluoroacetate or trifluoroacetic anhydride. Includes catalytic hydrogenation. For example, US Patent Nos. 3356746 and 3356747,
No. 3970710, No. 4396784 and Chemical Abstracts Vol. 85, Abst.
Please refer to No.123333y. In addition, U.S. Patent No. 4,311,863 to Gumprecht includes 2,
2,2-trifluoroethanol is a mixture of 2-chloro-1,1,1-trifluoroethane or 2-bromo-1,1,1-trifluoroethane and an alkali metal fluoride in the presence of water. It is disclosed that it can be obtained as a by-product of the reaction. 2, 2, in a continuous manner and in high yield by an efficient method.
It is an object of the present invention to provide a process capable of producing 2-trifluoroethanol and having a relatively simple method for recycling the 2,2,2-trifluoro-1-haloethane and optionally the organic acid salt or its acid form. This is highly desirable. SUMMARY OF THE INVENTION Applicants have now discovered that they can provide an improved process for the production of 2,2,2-trifluoroethanol that is economical, efficient and high yielding. In particular, Applicants provide 2,2,2
-Discovered a continuous production method for trifluoroethanol. Under spontaneous pressure or higher reaction pressure,
At reaction temperatures from about 223°C to about the critical temperature of the hydroxylated compound, 2-halo-1,1,1
- reacting trifluoroethane with a carboxylate salt and a hydroxylated compound to produce a reaction product mixture comprising 2,2,2-trifluoroethanol; At least a portion of the reaction product mixture is discharged from the reactor and unreacted 2-halo-1,1,1-trifluoroethane is separated from the discharged reaction product mixture. separated 2-halo-1,
1,1-trifluoroethane is recycled as at least a portion of the 2-halo-1,1,1-trifluoroethane fed to the reaction mixture and 2,2,2 from the remainder of the discharged reaction product mixture. ―
Collect trifluoroethanol. In one preferred embodiment of the invention, the discharged reaction product mixture is divided into two phases: a first phase containing a predominant amount of unreacted 2-halo-1,1,1-trifluoroethane; The main amount of 2,2,2-trifluoroethanol in the hydroxylated compound,
For example, the temperature is effective to produce a second phase contained in water. Separating the first phase from the second phase. The separated first phase is recycled as part of the 2-halo-1,1,1-trifluoroethane fed to the reaction mixture. 2,2,2-trifluoroethanol is recovered from the second phase, for example by distillation. In another aspect of the invention, the second phase is treated with an acid to convert the carboxylic acid salt in the second phase to its carboxylic acid form. The carboxylic acid is then separated from the second phase and a base is added thereto to regenerate the carboxylate salt and recycled as at least a portion of the carboxylate salt fed to the reaction mixture. The method of the invention provides a number of distinct benefits. In particular, the process of the invention can be carried out continuously in one reactor without the need for isolation of the intermediate, ie 2,2,2-trifluoroethyl acetate. The reaction is rapid and thus can be carried out efficiently. That is, a relatively high conversion rate can be obtained with a relatively short residence time. Moreover, there is no need for stirring, as in the Lawlor et al. patent, or special aprotic solvents, as in the Astrologes patent. In addition, in the method of the invention,
Internal recycling of unreacted 2-halo-1,1,1-trifluoroethane is possible. Furthermore, in one aspect of the present invention, such two
-Halo-1,1,1-trifluoroethane can be recycled without distillation and therefore no extra energy is required. For example, by the process of the invention using phase separation, the phase containing the major amount of unreacted 2-halo-1,1,1-trifluoroethane can be recycled to the reaction mixture under pressure. Such phase can be recycled internally, preferentially by gravity flow. Furthermore, depending on the salt used, the carboxylate salt can also be converted to its acid form, distilling the acid,
The acid is then fed into a base solution and reconverted to a salt to feed the carboxylate salt into the reaction mixture. Still further, the method of the present invention is economically advantageous because it can use an inexpensive stirrer-free tubular reactor. Since such inexpensive tubular reactors can be used, the corrosive nature of the reaction is less of a concern than in batch reactors using, for example, high-pressure stirred autoclaves. especially,
If replacement is desired or required, the tubular reactor can be replaced more easily and relatively economically than attempting to provide corrosion protection through the use of more expensive corrosion resistant alloys. The method of the present invention provides that the main product of the reaction is the desired 2,
It also provides environmental benefits as it is a 2,2-trifluoroethanol and environmentally friendly saline solution.
Carboxylate and unreacted 2-halo-1,1,1
-Other substances in the reaction, such as trifluoroethane, are preferably recycled. All these benefits make the method of the invention economically and environmentally desirable. DETAILED DESCRIPTION The method of the present invention is a continuous method for producing 2,2,2-trifluoroethanol. In the process of the invention, 2-halo-1,1,1-trifluoroethane (preferably 2-halo-1,1,1-trifluoroethane, also known as fluorocarbon 133a) and sodium acetate are used. and potassium and a hydroxylated compound (preferably water) selected from the group consisting of water, alcohols and glycols are continuously fed to the reaction mixture in the reactor. A general reaction is shown below. _{nCF 3 CH 2 _ _ _} M is an alkali metal or alkaline earth metal, and n is 1 or 2 depending on the valence of the metal M. For example, (RCO ₂ ) _o M can represent a carboxylate such as formate, acetate, carbonate, etc., R'OH can represent water or glycol, etc. The reaction mechanism using 2-chloro-1,1,1-trifluoroethane, acetate, and H ₂ O has been extensively studied. Applicants believe that this reaction is an exothermic, two-step reaction involving the intermediate 2,2,2-trifluoroethyl acetate (CH ₃ CO ₂ CH ₂ CF ₃ ), and that the intermediate compound is simply removed from the waterless reaction. I discovered that I can let go. This mechanism can be expressed by the equation below. _{CF3CH2Cl ＋ CH3CO2M _}
→CH ₃ CO ₂ CH ₂ CF ₃ +MCl CH ₃ CO ₂ CH ₂ CF ₃ +H ₂ O
→CF ₃ CH ₂ OH + CH ₃ CO ₂ H where M is an alkali metal cation. The process of the invention can be carried out in any reactor suitable for continuous operation, ie with continuous introduction of the reaction components and discharge of the reaction product mixture. Tubular reactors are preferred because of their convenience and relatively low cost. Preferably, the reactor, particularly the reactor surfaces that contact the reaction components, are comprised of a corrosion resistant material such as lncoloy 825. The reactor may be packed or unfilled.
For example, suitable packing materials for the reactor include polytetrafluoroethylene rings, metal packing, and the like. 2-halo-1,1,1-trifluoroethane may be a chloro or bromo or iodo compound. Bromo and iodo groups are better "leaving" groups, but availability and cost do not currently make these compounds economically possible. A preferred compound is 2-chloro-
1,1,1-trifluoroethane. Hydroxylated compounds that can be used in the process of the invention include any such hydroxylated compound that provides the necessary hydroxyl groups to hydroxylate or hydrolyze the reaction components to the desired 2,2,2-trifluoroethanol. included. Suitable hydroxylated compounds include water, alcohols, glycols, among others. Examples of suitable alcohols and glycols include lower alcohols such as ethanol, ethylene glycol, propylene glycol, glycerin. Water is the preferred hydroxylated compound. Suitable carboxylic acid salts for use in the present invention include the sodium, potassium, manganese, zinc, and magnesium salts of organic carboxylic acids, such as aliphatic and aromatic carboxylic acids. The carboxylic acid salt must be soluble in the solution to be added to the reactor and also at the reaction temperature. Examples of suitable organic acid salts include carbonates, formates, acetates, propionates, oleates, stearates, pelargonates, benzoates, phthalates and mixtures thereof. Preferably, the carboxylate salt is liquid at ambient temperature and does not substantially decompose at the reaction temperature. It is also preferred that the carboxylic acid can be distilled and recycled for further use in the reaction mixture, as explained further below. Preferred carboxylate salts include sodium acetate,
Contains potassium acetate. When using potassium acetate and 2-chloro-1,1,1-trifluoroethane, 2-chloro-1,1,1 of 1.0 or more
- It is preferred to use a molar ratio of trifluoroethane:potassium acetate. 2-halo-1,1,1-trifluoroethane is generally added neat to the reactor, but can be added as a solution if desired. Suitable solvents include any solvent that dissolves the 2-halo-1,1,1-trifluoroethane but does not react with any of the reaction components or products or decompose under the reaction conditions. If desired, a solvent can be used in addition to the reaction components, or the reaction can be carried out without added solvent. The solvent need not be the same as the solvent for 2-halo-1,1,1-trifluoroethane, if used. Various solvents for the reaction mixture can be used in the present invention. Suitable solvents include, for example, ethylene glycol diacetate, ethylene glycol dimethyl ether, or
Also included is 2-trifluoroethanol itself. The nature of the solvent can influence the multiphasic behavior of either the reaction mixture under reaction conditions and/or the reaction product mixture after cooling. The solvent can provide complete miscibility of the reaction components under the reaction conditions and also provide phase separation of the reaction product mixture after cooling. For example, when water is used as both a reaction component and a solvent, this miscibility can occur under reaction conditions near the critical temperature of water. Additionally, in general, in the presence or absence of additional solvent, solubilization of the reaction mixture can occur when the reaction conditions approach the critical conditions of the hydroxylated compound. When the solvent used gives a homogeneous reaction product mixture after cooling, recycling of the reaction components and/or recovery of the product can be carried out by any suitable means known in the art, such as distillation, solvent extraction,
This can be done by HPLC or the like. The carboxylic acid salt is usually added as a solution, preferably as a solution dissolved in the hydroxylated compound, more preferably as an aqueous solution having a PH of about 3 to about 10. More preferably, the carboxylate solution has a pH of about 4 to about 7. The carboxylate salt solution may be a buffered solution by using a combination of a carboxylate salt and its corresponding acid. The carboxylate salt can be formed in the reactor itself by adding a base solution to the reactor along with the carboxylic acid or its solution. However, even when recirculating a carboxylic acid such as acetic acid, it is necessary to first mix the carboxylic acid with a base or base solution to form a carboxylate solution for addition to the reactor to separate the base and acid. It is preferable to adding the hydride to the hydride, thus saving on pumps, controls, piping, etc. In one preferred embodiment of the invention, the reaction components are pressurized and preheated before being introduced into the reactor. The two reactant streams are pumped by any suitable means common in the art, for example by pressure pumps such as LEWA metering pumps and by hot oil or molten salts or fluidized solids or Dowtherm or other high temperature heat transfer media. can be pressurized and heated by heat exchange. Electric heaters or double heaters can also be used. For example, depending on the heat of reaction, a heat exchanger can be used to add heat to or remove heat from the system. Pressure systems can also be regulated and monitored using conventional pressure valves, pressure regulators, and pressure transducers, as is known in the art. In the process of the invention, the reaction components are fed to the bottom of a preferably vertically mounted tubular reactor;
-Halo-1,1,1-trifluoroethane is forced to pass through a denser hydroxylated compound at the reaction temperature. The process of the present invention may also employ a reflux-type apparatus in which the 2-halo-1,1,1-trifluoroethane is condensed and recycled under reaction pressure. The condensate, which may contain both hydroxylated compounds and 2-halo-1,1,1-trifluoroethane, is cooled, collected, separated into two phases, and the separated phases are recycled to the reactor. It can also be circulated. The reactor is pressurized to the reaction pressure at or above the spontaneous pressure of the reaction mixture itself. Preferably, the pressure within the reaction chamber is between ^{about 750} psig and about the critical pressure of the hydroxylated compound, more preferably at least about 1000 psig. , for example 77.33
~98.42Kg/ ^cm2 (1100~1400psig). The reactor temperature is also the reaction temperature from about 223° C. to the critical temperature of the hydroxylated compound. The lower temperature of this range represents the critical temperature of 2,2,2-trifluoroethanol. Since water is the preferred hydroxylated compound, the reaction temperature in this case ranges from about 223°C to about 374°C. The upper limit of this range represents the critical temperature of water. Preferably, the reaction temperature is at least about 250°C, more preferably at least 270°C. Temperature and pressure conditions are 2-halo-1,1,1
-trifluoroethane and the resulting product 2,2,
2-trifluoroethanol are chosen to exceed both their critical temperatures and critical pressures.
These conditions are preferably chosen such that the carboxylate salt and/or the solvent of the hydroxylated compound are also at or near their critical state. Thus, when water is used as the hydroxylated compound and as a solvent for the carboxylate salt, approximately
Pressures in excess of 70.3 Kg/cm ² gauge pressure (1000 psig) and temperatures in excess of about 250°C, more preferably about 270
Preference is given to operating at temperatures above .degree. In the method of the present invention, unreacted 2-halo-1,1,1
- Since the trifluoroethane is recycled, the % conversion per pass is less important than the total yield per unit time. Therefore, the reaction can be carried out at higher temperatures and shorter residence times to give high yields. Reacting component i.e. 2-halo-
The 1,1,1-trifluoroethane, carboxylate salt, and hydroxylated compound are typically combined at a production rate of at least about 40 g/hr/l, more preferably at least about 100 g/hr/l (reactor of 2,2,2-trifluoroethanol produced per hour per unit of reactor volume based on apparent volume). Passed. 200
Yields of 2,2,2-trifluoroethanol in excess of g/hr/l have been observed, and even higher yields are expected by optimizing reaction conditions. Typically, when using 2-halo-1,1,1-trifluoroethane, water, and acetate, the optimum residence time is from about 28 to about 56 mm based on reactor bulk volume, i.e., on an unpacked column basis. It's a minute. The actual residence time for a packed column will probably be about 1/2 of these times. Such residence times are high2,2,2
-Produces trifluoroethanol space velocity (or production) and high trifluoroethanol yield. When using 2-chloro-1,1,1-trifluoroethane, water and acetate, under the above conditions,
It is believed that the reaction is occurring in the aqueous phase and the rate of reaction depends on the solubility of 2-chloro-1,1,1-trifluoroethane in the carboxylate solution under the reaction conditions. As water approaches the critical state, the reaction mixture appears to behave as a homogeneous fluid. When 2-chloro-1,1,1-trifluoroethane and 2,2,2-trifluoroethanol are reacted under conditions exceeding their respective critical temperatures under these pressures, these Dramatically changes the solubility of organic substances in salt aqueous solutions. Similar results are expected for bromo and iodo compounds. Applicants' experiments show that excess, insoluble 2-chloro-1,1,1-trifluoroethane simply passes through the reaction system without any effect other than keeping the aqueous phase saturated. It shows. Excess insoluble 2-chloro-1,1,1-trifluoroethane also reduces the effective reaction volume. Carboxylate and 2-halo fed to the reactor
The molar ratio of 1,1,1-trifluoroethane affects the reaction rate and thus the yield. A suitable molar ratio of 2-chloro-1,1,1-trifluoroethane to carboxylate salt added is about 1:0.5 to about 1:10.0, more preferably about 1:0.9.
~about 1:1.1. 2-bromo-1,1,1-
Trifluoroethane and 2-iodo-1,1,
Similar molar ratios may be useful for 1-trifluoroethane. The use of the most economical reaction components and the maximum 2,2,2-trifluoroethanol production per unit time per unit of reactor volume is achieved, for example, at molar ratios as high as 1.4, with optimum values between 0.7 and 1.4. Obtained by using a feed of 2-chloro-1,1,1-trifluoroethane and sodium acetate. However, when potassium acetate is used as the carboxylate salt, it is preferred to use a molar ratio of 2-chloro-1,1,1-trifluoroethane to potassium acetate greater than 1.0. The carboxylate salt is preferably fed to the reactor as a solution, most preferably as an aqueous solution. However, other solvents for the carboxylic acid can also be used as long as some hydroxylated compound is present, again preferably water. Additionally, molten salts such as sodium acetate trihydrate can also be used. Thus, as used herein and in the claims, feeding a reaction mixture of a carboxylic acid salt and a hydroxylated compound is also intended to include feeding, for example, a solvent salt hydrate, such as sodium acetate trihydrate. In this connection, it has been discovered that hydroxylated compounds are necessary to give the desired end products. If no hydroxylated compounds are present,
Esters such as 2,2,2-trifluoroethyl acetate may be isolated as the main product. At least a portion of the reaction product mixture is continuously discharged from the reactor. In this context, a reaction product mixture is one in which the reaction components, products, etc. discharged from the reactor are miscible, e.g. due to the reaction components, products themselves, the solvent used, temperature, pressure, etc. This shall cover the state in which it may also be unsaturated. Thus, the reaction product “mixture”
may be one-phase or multi-phase. Typically, in the case of a tubular reactor, the amount of reaction product mixture that is continuously discharged is determined by the flow rate of the reaction components entering the reactor, i.e., the reaction product mixture exiting the reactor. , which also depends on the desired residence time of the reaction components. Preferably, the reaction product mixture is discharged from the reactor under pressure, preferably under reaction pressure. In the process of the invention, unreacted 2-halo-1,1,1-trifluoroethane is separated from the discharged product mixture and 2-halo-1,1,1-trifluoroethane is fed to the reaction mixture.
It is recycled to the reactor as a portion of halo-1,1,1-trifluoroethane. Separation can be carried out by any means suitable for use in a continuous process. For example, unreacted 2-halo-1,1,1-trifluoroethane can be distilled from the discharged reaction product mixture and recycled to the reaction mixture. Preferably, however, in the absence of a homogeneous solvent, the discharged reaction product mixture is composed of a first phase containing a predominant amount of unreacted 2-halo-1,1,1-trifluoroethane and a predominant amount of unreacted 2-halo-1,1,1-trifluoroethane. and a second phase containing an amount of 2,2,2-trifluoroethanol. This two phase allows easy and efficient separation of unreacted 2-halo-1,1,1-trifluoroethane for recycling. Furthermore, the reaction pressure can be maintained during phase separation and internal recirculation is possible by simple gravity return flow. Another important discovery of the method of the invention is that 2-
Chloro-1,1,1-trifluoroethane, water,
In the case of acetate, an inversion of relative density occurs at a temperature and reaction pressure of about 130°C. The phase containing the predominant amount of unreacted 2-chloro-1,1,1-trifluoroethane is normally more dense than the product aqueous phase, but above this temperature it becomes less dense than the product aqueous phase. Become. It has been discovered that this density inversion is of great importance in the method of the invention. especially,
Due to the density inversion mentioned above, the main amount of unreacted 2
The phase containing -chloro-1,1,1-trifluoroethane can exit as an upper phase or as a lower phase. Thus, 2-chloro-
The 1,1,1-trifluoroethane-containing phase is the upper phase at temperatures above about 130°C under typical pressure conditions and is the upper phase at temperatures below about 130°C under such pressure conditions. It is the lower phase. Therefore, the temperature of the discharged reaction product mixture is determined by the main amount of unreacted 2-
The temperature can be sufficient to form a phase containing chloro-1,1,1-trifluoroethane as either the upper phase or the lower phase. Preferably,
The fluid discharged from the reactor is cooled below such inversion temperature to facilitate phase separation. In this connection, having a phase containing a predominant amount of 2-chloro-1,1,1-trifluoroethane as an underlying layer can be
Phase separation is facilitated in that this phase can be easily recycled to the reactor by simple gravity flow under reaction pressure. A number of benefits are obtained by using phase separation to separate the major amount of unreacted 2-halo-1,1,1-trifluoroethane from the remaining amount of the reaction product mixture. In particular, unreacted 2-halo-
It is not necessary to isolate the 1,1,1-trifluoroethane, but rather it can be recycled internally (ie within the reactor system) under pressure. moreover,
It provides relatively pure unreacted 2-halo-1,1,1-trifluoroethane for recycling to the reactor without the need for distillation or the energy required therefor. Thus, the continuous process of the present invention using such phase separation and recycling provides an economically advantageous and highly efficient continuous process for the production of 2,2,2-trifluoroethanol. Of course, since the method of the present invention is a continuous method, the first
It will be appreciated that while the phase and the second phase are produced continuously, typically only a portion of the first phase is recycled at any particular point in the continuous process.
In other words, during operation of the continuous manufacturing process of the present invention, there will almost always be a first phase and a second phase in the collection chamber, with a portion of the first phase being discharged from the collection chamber and recycled to the reactor. It is being done. In particular, at the beginning of the continuous process of the present invention, the discharged reaction product mixture may contain relatively large amounts of unreacted 2-halo 1,1,1-trifluoroethane. Since 2,2,2-trifluoroethanol is not completely confined in the aqueous phase, there may be little 2,2,2-trifluoroethanol in the aqueous phase under such conditions. The relative amounts of 2,2,2-trifluoroethanol accumulate and therefore increasingly larger amounts are found in the aqueous phase. On the other hand, even when a considerable amount of 2,2,2-trifluoroethanol is produced, some 2,2,2-trifluoroethanol Extract. Thus, recycling of 2-halo-1,1,1-trifluoroethane is minimized, i.e.
It is desirable to carry out the reaction while maximizing the conversion rate of -halo-1,1,1-trifluoroethane. Phase separation can be accomplished by any suitable means. For example, at bench scale, a viewing window in a T-pipe can be used to observe the separated phases. Preferably, 2-halo-1,1,1-
Separation of the trifluoroethane-containing phase can be achieved by e.g.
Automatically controlled with conventional interfacial level control devices based on acoustic waves, pressure change sensing or other suitable phase sensing devices. In one preferred embodiment of the invention, the carboxylate salt is recycled. For example, a secondary product containing a predominant amount of 2,2,2-trifluoroethanol
The phase (usually the aqueous phase) contains most, if not all, of the carboxylate salt. This second phase can be treated with an acid such as HCl to convert the carboxylate salt to the carboxylic acid form. This carboxylic acid can then be separated from the second phase by means conventional in the art. For example, if the carboxylic acid is distillable, it can simply be distilled from the second phase and returned directly to the reactor. Alternatively, such distilled acid can be converted back to the carboxylate salt form by first mixing with a base solution. This carboxylate solution can then be added to the reactor. With some acids, such as acetic acid, salting out effects can occur, so the strong acetic acid solution can be distilled off from the remainder of the aqueous phase. If the carboxylic acid is not distillable, it can be extracted from the second phase, for example by means of a suitable solvent. The carboxylic acid can then be extracted from the solvent with a base solution. In this case, the soluble salt of the carboxylic acid is regenerated in the basic solution. Again, such a carboxylate solution can be used for feeding the carboxylate to the reaction mixture. If phase separation is not used, the carboxylic acid (if distillable) can be fractionated from the reaction product mixture. Additionally, if a significant portion of the carboxylic acid is present in the first phase, this carboxylic acid can be recycled with the first phase as described above. The desired 2,2,2-trifluoroethanol can be recovered by any means conventional in the art.
For example, 2,2,2-trifluoroethanol can be distilled from the reaction product mixture discharged from the reactor. This distillation may be carried out directly from the reaction product mixture, or it may be carried out first by phase separation of one or more of the reaction components or by-products. For example, when separating the first phase and the second phase as described above, 2,2,2-trifluoroethanol can be distilled from the second phase after being separated from the first phase. , thus converting 2,2,2-trifluoroethanol to unreacted 2-halo-1,
After distilling 1,1-trifluoroethane, 2,
The possibility of having to distill the 2,2-trifluoroethanol again can be avoided. Additionally, 2,2,2-trifluoroethanol can be distilled from such a second phase before or after addition of the acid for recycling of the carboxylate salt. For example, if the carboxylate salt is acetate, hydrochloric acid or other acid can be added to convert the acetate to acetic acid. The 2,2,2-trifluoroethanol can be distilled before addition of the acid, or can be fractionated with the acetic acid formed after the addition of such acid. Preferably, the process of the invention is carried out such that the recycled unreacted 2-halo-1,1,1-trifluoroethane is under pressure, preferably under reaction pressure. Thus, the method of the invention includes a continuous evacuation step, a step of attaining a temperature sufficient to provide the first and second phases, and a step of separating the first and second phases. The step of recycling the separated first phase to the reaction mixture is carried out under pressure, preferably under reaction pressure. Furthermore, the evacuation step, the raising to sufficient temperature step, the separation step, and the recirculation step are carried out continuously. Figure 1 shows the use of 2-chloro-1,1,1-trifluoroethane as 2-halo-1,1,1-trifluoroethane, sodium acetate as the carboxylate salt, and water as the hydroxylated compound. broadly exemplify the method of the present invention. FIG. 1 shows a trifluoroethanol plant in the process of the invention. All that must be supplied to the plant is 2-chloro-1,
1,1-trifluoroethane, base (e.g. sodium hydroxide, preferably in minimal amounts close to stoichiometric equivalents), acetic acid (preferably glacial acetic acid) as required for initiation and/or make-up, PH adjustment. An acid such as hydrochloric acid is required for Thus, within the trifluoroethanol plant (FIG. 1) acetate is recycled internally as well as unreacted 2-chloro-1,1,1-trifluoroethane. Thus, crude 2,2,2-trifluoroethanol and a salt solution such as sodium chloride solution are essentially the only materials discharged from plant 1. The environmental benefits of the process of the invention are clear, since fundamentally only the desired end product and a relatively environmentally benign sodium chloride solution are produced. A more detailed illustration of one embodiment of the invention is shown in FIG. In the system shown in Figure 2, the process of the invention is illustrated for a process using the also preferred reactants, namely 2-chloro-1,1,1-trifluoroethane and aqueous sodium acetate. In FIG. 2, the introduction of reaction components and the discharge of products are indicated by dark lines. 2-Chloro-1,1,1-trifluoroethane is fed to the reactor 2 from a storage tank 3 which is normally under pressure due to the low boiling point of the starting material. 2-
The chloro-1,1,1-trifluoroethane is transferred through line 4, pump 5 (which further pressurizes the 2-chloro-1,1,1-trifluoroethane), and a suitable heat exchanger 7 [implementation shown in the figure]. The embodiment uses a Dowtherm system 8 as the high temperature heat exchange medium for the heat exchanger through line 9]. Pump 5 may be any suitable pump for providing high pressure, such as a LEWA metering pump. Suitable pressure valves and pressure transducers can be used to control and monitor pressure. The aqueous sodium acetate solution is fed from the storage tank 10 to the reactor 2 through a line 11, a pump 12, and a line 13 passing through a heat exchanger 14. Again, conventional heat exchangers and pumps can be used to provide the desired high temperatures and pressures. In the embodiment shown, heat exchanger 14 is supplied with high temperature heat exchange medium from a Dowtherm device via line 15. Sodium acetate is stored as is in storage tank 10.
or can be prepared by mixing acetic acid and aqueous sodium hydroxide, supplied as starting or make-up glacial acetic acid or as recycled acetic acid as described above. The temperature of reactor 2 is also controlled. In the embodiment shown, this temperature is controlled by a heat exchange fluid sent from a Dowtherm device 8 through line 16 to the reactor. Since the reaction is exothermic, this heat exchange in the reactor can heat or cool the reactor as and when required. The reactor 2 may be of a packed type or an unfilled type, as desired. In the reactor, the temperature and pressure of the reaction mixture were adjusted such that the reaction temperature was between about 223°C and the critical temperature for this water (i.e. 374°C) and the reaction pressure was about 52.725 Kg/cm ² gauge. pressure (750 psig) to the near critical pressure of water, in most cases
Control so that the pressure is 70.3Kg/ ^cm2 gauge pressure (1000psig) or higher. Within the reactor 2, the density inversion described above takes place. In particular, 2-chloro-1,1,1-trifluoroethane is typically more dense than water. However, due to density inversion at high temperatures, 2-chloro-
1,1,1-trifluoroethane supercritical fluid has a lower density than water. In the vertical tubular reactor, due to this density inversion, 2-chloro-1,1,1-trifluoroethane has no choice but to pass through the higher density aqueous component, as shown in Figure 2. , facilitating the reaction. The reaction product mixture is transferred from reactor 2 to line 17
In the embodiment shown in FIG.
It is sent to the top of the cold water cooler 18 essentially at reaction temperature and cooled to the appropriate temperature to produce the two phases. The cooled reaction product mixture is transferred to tank 19
is collected therein, where a first phase and a second phase are formed. In this case, if the temperature of the reaction product mixture in the collection tank is below about 130°C, the lower phase (first phase)
contains a major amount of unreacted 2-chloro-1,1,1-trifluoroethane, and the upper aqueous phase (second phase) contains a major amount of the desired product 2,2,2-trifluoroethanol. . In the embodiment shown in FIG.
1,1,1-trifluoroethane can be separated from the aqueous phase containing most 2,2,2-trifluoroethanol by simple phase separation. The separated first phase is then returned to the reaction mixture in reactor 2 through line 20 by gravity flow. The second phase containing the major amount of 2,2,2-trifluoroethanol product is discharged from collection tank 19 through line 21 and through pressure reducing valve 22 .
In the embodiment shown in FIG. 2, the second phase is distilled directly in still 23 and the crude 2,2,2-trifluoroethanol product is passed through line 24, cold water cooler 25, and line 26. It passes through and is collected. The distiller 23 is heated, for example by a steam heat exchanger 27 or in any other conventional manner. Residue from the still is collected through line 28 and sent through line 30 to a second still 29. An acid, such as hydrochloric acid, is added to distiller 29 from line 30 to convert the acetate to its acetate form. In distiller 29, acetic acid is distilled and collected through line 31, cold water cooler 32. The obtained acetic acid aqueous solution is transferred to line 33.
through the sodium acetate storage tank 10. The distiller 29 can be heated with any conventional heat exchange device, in the example shown a steam heat exchange device 34 is used. Essentially, the only product collected from the bottom of still 29 is a relatively environmentally benign sodium chloride solution. This can be treated to recover the sodium chloride, if desired, or it can be dumped as is. A dotted line 35 indicates a region where the reaction temperature is maintained in the reaction system, and a chain line 36 indicates a region where the reaction pressure is maintained in the reaction system. The examples shown below are intended to illustrate the method of the present invention, but are not intended to limit the method of the present invention. Example 1 A 106.68 cm (42 in) long unfilled Ni alloy reaction tube, of which 81.28 cm (32 in) was in an electric furnace, was installed vertically. The reaction tube has an outer diameter of 2.54 cm (1 inch),
The wall thickness was 1.651 mm (0.065 in). Above the reactor tube
A 12.7cm (5in) section was insulated. This reaction tube
After pressurizing with deionized water to about 87.875-94.905 Kg/cm ² gauge pressure (1250-1350 psig), it was heated to about 20° C. below the reaction temperature in preparation for the next expected exotherm. 30% by weight aqueous sodium acetate solution at PH 6 and 2-chloro-1,1,1-trifluoroethane into the bottom of the reaction tube, independently and continuously.
It was fed by a dual head metering pump. The reaction mixture fed to the reaction tube is preheated with a heating tape on the feed line. The reaction takes place without stirring in a reaction tube. The temperature of the reactor tubes is controlled by two manually regulated power stat's for the two zones of the reactor tube furnace and by automated equipment including a digital temperature regulator, amperage regulator (SCR), and a third For zones it was regulated by thermocouples. A regulating thermocouple was placed in the final zone of the furnace. Thus, temperatures and pressures during the various experiments were adjusted as shown in Table 1 below. The fluid exits the reaction tube and is sent to a water-cooled phase separator.
The upper aqueous phase is treated with a pressure let down device.
system) to three low-pressure traps in sequence. The first trap is at ambient temperature, the second trap is 0°C, and the third trap is -78°C.
It was hot. The lower organic phase was manually routed through two metering valves into the second trap. All the material collected in the third totsurap was analyzed by gas chromatography. The product was collected at regular time intervals, also as shown in Table 1 below.
Feed rate, residence time of 2-chloro-1,1,1-trifluoroethane and sodium acetate solution,
Molar ratio of 2-chloro-1,1,1-trifluoroethane to sodium acetate and water, PH of sodium acetate solution, total reaction time, product collection time, conversion (%), yield (%), The yields for the various experiments are shown in Table 1 below.

【table】

[Table] Example 2 A series of experiments were carried out following procedures similar to those described in Example 1. However, instead of a reaction tube, a 7 mm borosilicate glass Raschig ring or
4.064mm (0.16in) Stainless Steel 316 “Protrusion” Column Packing or OD 3.96875mm (5/32in), ID 2.38125mm (3/32in), Length 3.175mm (1/8in)
A vertical reaction tube filled with polytetrafluoroethylene rings was used. Additionally, one experiment used a recycle stream of unreacted 2-chloro-1,1,1-trifluoroethane to remove 2-chloro-1,1,1-trifluoroethane from the cooled, collected product mixture. Trifluoroethane was recycled to the reaction tube by a LEWA pump. The top of the reaction tube was insulated with black cellular glass insulation. Reaction conditions and results are shown in Table 2 below. The residence time and the amount of 2,2,2-trifluoroethanol produced were calculated based on the apparent capacity of the reaction tube (without packing).

【table】

[Table] Example 3 Using the procedure described in Example 2 above, an aqueous potassium acetate solution was used in place of the sodium acetate solution. The reaction tube was filled with polytetrafluoroethylene rings. Potassium acetate was the limiting reagent and excess 2-chloro-1,1,1-trifluoroethane was introduced. The reaction conditions and results are shown in Table 3 below.

【table】

[Table] Example 4 A series of reactions were carried out in the same manner as in Example 1 in an unfilled horizontally mounted reaction tube, such as an Incoloy 825 tube, with an outer diameter of 2.54 (1 inch) and an inner diameter of 2.2098 cm (0.87 inch). I went. The center 81.28 cm (32 in) of the total length of 121.92 cm (48 in) was placed in an electric furnace to control the reaction temperature. Three graphite-filled metering valves in series were used as pressure reduction devices to reduce the pressure of the reaction product mixture. The reaction tube was prefilled with deionized water and a dual-head metering pump was used to reach the desired pressure. The system was preheated to a reaction temperature of at least 225°C. A 30% aqueous sodium acetate solution with a constant pH value and 2-chloro-1,1,1-trifluoroethane were independently and continuously supplied into the reaction tube using a metering pump. The reaction took place in this heated tube without additional stirring. The reaction temperature was automatically regulated with a digital temperature controller, and a thermocouple sensing amperage regulator (SCR) was inserted axially into the center of the heated section of the reaction tube. Pressure was adjusted manually by adjusting three metering valves. The outlet stream is air cooled, with the first trap at ambient temperature and the second trap at 0.
℃, and the third trap was continuously collected in three consecutive traps at -78℃. The material collected in all three traps was analyzed by gas chromatography.
The reaction conditions and results are shown in Table 4 below.

【table】

[Table] ○R
11 Incoloy 825 was used.
It goes without saying that the embodiments described above are representative examples, and that those skilled in the art can make many changes and modifications without departing from the spirit and scope of the invention. All such changes and modifications are intended to be included within the scope of the invention as defined by the following claims.

[Brief explanation of drawings]

FIG. 1 is a block diagram broadly illustrating one embodiment of the method of the invention, and FIG. 2 is a schematic diagram of an apparatus for carrying out one embodiment of the method of the invention.

Claims (1)

[Scope of Claims] 1 2-halo-1,1,1-trifluoroethane, a carboxylate selected from the group consisting of sodium and potassium acetate, and selected from the group consisting of water, alcohol and glycol. continuously feeding a hydroxylated compound to a reaction mixture in a reactor, and reacting in the reactor under autogenous pressure or higher reaction pressure and from 223° C. to the critical temperature of the hydroxylated compound. reacting the 2-halo-1,1,1-trifluoroethane, the carboxylic acid salt, and the hydroxylated compound at a temperature to form a reaction product mixture containing 2,2,2-trifluoroethanol. continuously discharging at least a portion of the reaction product mixture from the reactor; and discharging unreacted 2-halo-1,1,1- from the discharged reaction product mixture.
a step of separating trifluoroethane, and supplying the separated unreacted 2-halo-1,1,1-trifluoroethane to the reaction mixture;
recycling 1,1-trifluoroethane as a portion, provided that the continuously discharging step
(separation step, recycling step carried out under pressure) and from the remainder of the discharged reaction product mixture 2,2,2
- A method for continuous production of 2,2,2-trifluoroethanol, comprising a step of recovering trifluoroethanol. 2. The manufacturing method according to claim 1, wherein the 2-halo-1,1,1-trifluoroethane is 2-chloro-1,1,1-trifluoroethane. 3 Unreacted 2 from the discharged reaction product mixture
Claim 2 in which the continuous separation of chloro-1,1,1-trifluoroethane is carried out by fractional distillation.
Manufacturing method described in section. 4 Mixing carboxylic acid with base solution and obtaining
3. The process according to claim 2, wherein the carboxylic acid salt is fed to the reactor by feeding a solution with a pH of 3 to 10 to the reaction mixture. 5. The method of claim 2, wherein the hydroxylated compound comprises water. 6. The production method according to claim 5, wherein the reaction temperature is in the range of 223°C to 374°C. 7. The production method according to claim 1, wherein the pressure is the reaction pressure or a pressure near the reaction pressure. 8. The production method according to claim 2, wherein 2-chloro-1,1,1-trifluoroethane and the carboxylic acid salt are supplied to the reaction mixture in a molar ratio of 1:0.5 to 1:10.0. 9. The production method according to claim 2, wherein 2-chloro-1,1,1-trifluoroethane and the carboxylic acid salt are supplied to the reaction mixture in a molar ratio of 1:0.9 to 1:1.1. 10. The production method according to claim 2, wherein the carboxylate is sodium acetate. 11. The production method according to claim 2, wherein the carboxylate is potassium acetate. 12 2-chloro-1, supplied to the reactor
12. The manufacturing method according to claim 11, wherein the molar ratio of 1,1-trifluoroethane to potassium acetate is 1.0 or more. 13. The production method according to claim 2, wherein the reaction temperature is at least 250°C. 14. The production method according to claim 2, wherein the reaction temperature is at least 270°C. 15. The method of claim ² , wherein the reaction pressure is from 750 psig to the critical pressure of the hydroxylated compound. 16. The method of claim 2, wherein the reaction pressure is at least 70.3 Kg/cm ² gauge pressure (1000 psig).